Users Guide

Configure a Route Map for Route Tagging................................................................................150
Continue Clause..........................................................................................................................150
Configuring a UDF ACL.....................................................................................................................150
Hot-Lock Behavior............................................................................................................................152
7 Bidirectional Forwarding Detection (BFD)...................................................153
How BFD Works................................................................................................................................ 153
BFD Packet Format......................................................................................................................154
BFD Sessions................................................................................................................................156
BFD Three-Way Handshake........................................................................................................156
Session State Changes.................................................................................................................157
Important Points to Remember........................................................................................................158
Configure BFD...................................................................................................................................158
Configure BFD for Static Routes.................................................................................................159
Configure BFD for OSPF............................................................................................................. 160
Configure BFD for OSPFv3......................................................................................................... 164
Configure BFD for IS-IS...............................................................................................................165
Configure BFD for BGP...............................................................................................................168
Configure BFD for VRRP..............................................................................................................174
Configuring Protocol Liveness....................................................................................................177
8 Border Gateway Protocol IPv4 (BGPv4).......................................................178
Autonomous Systems (AS)................................................................................................................178
Sessions and Peers............................................................................................................................180
Establish a Session....................................................................................................................... 181
Route Reflectors................................................................................................................................181
Communities............................................................................................................................... 182
BGP Attributes................................................................................................................................... 182
Best Path Selection Criteria.........................................................................................................183
Weight..........................................................................................................................................185
Local Preference......................................................................................................................... 185
Multi-Exit Discriminators (MEDs)................................................................................................186
Origin........................................................................................................................................... 187
AS Path.........................................................................................................................................188
Next Hop..................................................................................................................................... 188
Multiprotocol BGP............................................................................................................................ 188
Implement BGP ................................................................................................................................189
Additional Path (Add-Path) Support........................................................................................... 189
Advertise IGP Cost as MED for Redistributed Routes................................................................ 189
Ignore Router-ID for Some Best-Path Calculations..................................................................190
Four-Byte AS Numbers............................................................................................................... 190
AS4 Number Representation...................................................................................................... 190
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